In preparation for next week’s launch, the Android Market now lets developers test in-app billing for their Android apps. The developer console has a feature that lets devs interact with the Android Market as if a customer was really purchasing items, such as better weapons in a shooting game or new levels in a puzzle. This gives developers time to test their implementation before the feature rolls-out to Android phones beginning next week.

In-app billing will allow developers to charge for certain features directly through the app. For example, Glu Mobile will let Gun Bros players purchase better weapons and feature upgrades without having to wait for rewards earned through gameplay. This could also lead to other developers choosing to release standard versions of their app for free and provide additional features through $1 dollar upgrades rather than relying on free “Lite” and costly premium versions.

Google has repeatedly stated that the Android Market would support in-app purchases, but would only say “soon” until now. Android Market lead Eric Chu states that Android app developers can upload their wares and test in-app billing right now. Developers are strongly urged to begin testing and ensuring that their new apps meet the security guidelines set forth by Google. More information can be found here.